Methods for the removal of acidic gases from gaseous mixtures employing methanol as the wash liquid are known, such as is shown in DE-OS No. 27 59 123. The method described in this patent application uses washing liquids such as methanol for the separation of acidic gases from gaseous mixtures. This washing is primarily accomplished with ammonia, which can increase the effectiveness thereof. However, with respect to the upper limits for the use of such additional ammonia therein, it is required that the ammonia concentration be not more than 0.5 weight percent in the washing liquid. This stringent requirement is said to be based upon the fact that at higher ammonia concentrations, the solid precipitate of ammonium compounds is observed. Therefore, based upon these relatively low permissible ammonia concentrations, it is possible by employing a cleaning column of relatively narrow dimensions to obtain a satisfactory cleaning with minute concentrations of acidic gases remaining in the washed gas. A noticeable decrease in the demands for washing liquid and a reduction of the amount of hydrocarbons unintentionally solved during the treatment of gases containing the same cannot be achieved with these small ammonia additions.
It is therefore an object of the present invention to provide a method of this type which, however, achieves improved efficiencies of operation thereover. In particular, this is desired with respect to the undesired co-absorption of hydrocarbons.